Re: [TLS] Draft updates: tls-dnssec-chain

On Sat, Apr 28, 2018 at 1:52 PM Viktor Dukhovni <ietf-dane@dukhovni.org>
wrote:

>
>
> > On Apr 28, 2018, at 12:19 PM, Shumon Huque <shuque@gmail.com> wrote:
> >
> >    This specification can also be used to optionally convey
> >    authenticated denial of existence of TLSA records.  Restrictive uses
> >    that might require such proofs (such as the PKIX constraining modes
> >    of DANE, or where DANE should always be preferred over other modes of
> >    authentication such as traditional PKIX) are thus not in its intended
> >    scope.  Such restrictive uses can however be supported
> >    opportunistically.
>
> The last sentence makes no sense.  The term "Restrictive uses" is poorly
> defined.  The reduction in scope is effectively a reduction to just the
> cases where the extension is mandatory, if that's what you intend to do
> then say so (expect pushback).
>
> Please do not imply that any non-mandatory "additive" use-cases are
> viable.  They are not.
>

I agree with Viktor here.

You could imagine enforcing a restriction you see in a DANE extension the
cert you get milliseconds later, but that's pretty useless given that an
attacker can just not send the extension.  Let's just scope this to the
additive case.

>
> --
>         Viktor.
>
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